keep the level of light with LDR

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lonkenzo

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Hello,
i would like to get a circuit wich use an LDR to provide the level of light in a room. My problem is that generally an LDR is use to get a binary information( light on or off).
I want each time to know what is the information about the light level stored in a voltage or a current.
Thank you
 

LDRs are analog devices, their resistance is proportional to the amount of light falling on them. They can be used to produce binary levels but only in some opto-isolator applications or where they are followed by a comparator circuit.

I have even used them to maintain constant light levels in a design that automatically opened and closed horizontal window blinds.

The get a voltage or current measurement, connect the LDR in a bridge configuration or as a potential divider with other resistances being fixed values. You can then scale the voltage with an amplifier and measure it with a meter or an ADC.

Brian.
 

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